Part A
74HC259D
Toshiba Halbleiter und Speicher
- Lifecycle
- Active
- Stock
- 7207 Stückzahl
- Package
- SOIC-20
- Series
- Logic-Verriegelungen
Replacement verdict
Not a drop-in replacement
The 74HC259D and 74HC251D-Q100J are functionally distinct logic ICs and cannot serve as substitutes for one another. The 74HC259D is an 8-bit addressable latch with a single data input and eight individually addressable outputs, while the 74HC251D-Q100J is an 8-input multiplexer with three select lines and a single 3-state output. Their internal architectures, pin functions, and logic operations differ fundamentally, making direct replacement impossible without complete circuit redesign.
Different logic function
Different output configuration
Different pin function assignment
Different input signal topology
Parts at a glance
Part B
74HC251D-Q100J
Nexperia USA Inc.
- Lifecycle
- Active
- Stock
- 6040 Stückzahl
- Package
- SOIC-16
- Series
- Logic.Signal Schalter, Multiplexer, Decoder
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | 74HC259D | 74HC251D-Q100J | Why it matters |
|---|---|---|---|
| Logic Function | 8-bit addressable latch | 8-input multiplexer with 3-state output | The core function differs; one latches and stores addressed bits while the other selects one of eight inputs, so they are not functionally interchangeable. |
| Output Type | Standard CMOS latch outputs (Q and Q-bar) | 3-state non-inverting output (Y) and complementary output (W) | 3-state outputs allow bus sharing, whereas the latch outputs are always driven, affecting system architecture and wiring. |
| Number of Outputs | 8 latched outputs | 1 selected data output (plus complement) | The latch provides eight stored outputs, while the multiplexer routes one of eight inputs to a single output, determining how many signals can be handled. |
| Number of Inputs | 1 data input plus 3 address inputs | 8 data inputs plus 3 select inputs | Input count and addressing scheme differ, affecting how many source signals can be connected and selected. |
| Enable/Strobe Control | Active-low enable (E-bar) for latching | Active-low output enable (OE-bar) for 3-state | The enable pin controls different behaviors: latching in one device versus high-impedance output in the other. |
| Supply Voltage Range | 2.0 V to 6.0 V | 2.0 V to 6.0 V | Both operate over the standard HC-family supply range, so power supply compatibility is identical. |
| Logic Family | 74HC (high-speed CMOS) | 74HC (high-speed CMOS) | Same logic family ensures comparable input thresholds, noise margins, and drive characteristics. |
| Qualification/Automotive Grade | Standard commercial grade | AEC-Q100 qualified | The Q100J variant is automotive-qualified, which is critical for automotive and high-reliability applications. |
| Package | SO16 (SOIC-16) | SO16 (SOIC-16) | Although both use a 16-pin SOIC package, pinout and function differ, so footprint compatibility does not guarantee interchangeability. |
| Propagation Delay (typical at 5 V) | Approximately 15 ns | Approximately 13 ns | Timing differences can affect setup/hold margins and maximum operating frequency in synchronous designs. |
Need help validating a replacement?
Send your BOM and application constraints for technical and sourcing review.
Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 74HC259D | 74HC251D-Q100J |
|---|---|---|
| Supplier | - | Nexperia USA Inc. |
| Series | 74HC | Automotive, AEC-Q100, 74HC |
| Part Status | Active | Active |
| Type | - | Multiplexer |
| Circuit | 1:8 | 1 x 8:1 |
| Independent Circuits | 1 | 1 |
| Current - Output High Low | 5.2mA, 5.2mA | 5.2mA, 5.2mA |
| Voltage Supply Source | - | Single Supply |
| Voltage - Supply | 2V ~ 6V | 2V ~ 6V |
| Operating Temperature | -40°C ~ 125°C | -40°C ~ 125°C |
| Mounting Type | Surface Mount | Surface Mount |
| Logic Type | D-Type, Addressable | - |
| Output Type | Standard | - |
| Delay Time - Propagation | 22ns | - |
Frequently asked questions
What are the primary functional differences between the 74HC259D and 74HC251D-Q100J?
The 74HC259D is an 8-bit addressable latch that stores single-bit data to one of eight outputs selected by a 3-bit address. The 74HC251D-Q100J is an 8-input multiplexer with a 3-state output, which selects one of eight data inputs based on a 3-bit address and routes it to a single output. They serve different logic functions: latching/demultiplexing versus data selection/multiplexing.
Are the 74HC259D and 74HC251D-Q100J pin-compatible?
No. The 74HC259D is typically supplied in a 16-pin SOIC package, while the 74HC251D-Q100J is supplied in a 16-pin SOIC package as well, but their pin functions differ. The 74HC259D has eight outputs (Q0–Q7), a latch enable, a clear input, and a data input. The 74HC251D-Q100J has eight data inputs (I0–I7), a 3-state output (Y), an enable input, and a complementary output (W). Therefore, they are not pin-to-pin compatible despite similar package sizes.
Can the 74HC259D be used as a drop-in replacement for the 74HC251D-Q100J in an existing design?
No. The two devices have different logic functions, pinouts, and control signals. The 74HC259D cannot perform multiplexing, and the 74HC251D-Q100J cannot perform latching. A direct substitution would require redesigning the circuit and validating all timing, voltage, and functional requirements against the respective manufacturer datasheets.
What are the key electrical specifications for the 74HC259D?
Per manufacturer datasheets, the 74HC259D operates over a supply voltage range of 2.0 V to 6.0 V, has typical propagation delay of 15 ns at 4.5 V, and provides standard CMOS output drive. It is a non-Q100 device, meaning it is not automotive-qualified. Exact limits should be verified from the specific manufacturer datasheet (e.g., Nexperia, Texas Instruments, or ON Semiconductor).
What are the key electrical specifications for the 74HC251D-Q100J?
The 74HC251D-Q100J is a Q100-qualified automotive-grade device. It operates over a supply voltage range of 2.0 V to 6.0 V, features a 3-state output, and has typical propagation delay of 14 ns at 4.5 V. The Q100 suffix indicates compliance with AEC-Q100 requirements for automotive applications. Exact parameters should be confirmed from the manufacturer datasheet (e.g., Nexperia).
What is the difference in output configuration between the two devices?
The 74HC259D provides eight parallel latched outputs (Q0–Q7), each capable of driving a logic load. The 74HC251D-Q100J provides one 3-state output (Y) and one complementary output (W), allowing the selected input to be routed to a single bus line with high-impedance capability when disabled. This makes the 74HC251D-Q100J suitable for bus multiplexing, while the 74HC259D is suited for addressable storage or demultiplexing.
Which device is better suited for automotive applications?
The 74HC251D-Q100J is specifically qualified to AEC-Q100 for automotive use, making it the appropriate choice for automotive designs. The 74HC259D is a standard commercial/industrial-grade device and is not automotive-qualified. Designers should verify the exact qualification status from the manufacturer’s datasheet before use in automotive systems.
Do both devices support the same operating temperature range?
Both devices are typically specified for the standard industrial temperature range of –40 °C to +125 °C, but the 74HC251D-Q100J may have additional automotive temperature grade options. The 74HC259D is generally rated for –40 °C to +125 °C as well. Always confirm the exact temperature range from the specific manufacturer datasheet, as it can vary by supplier and package.